Prior to a recent conversation the librarians had with with our Instructional Technology Coordinator, David Jakes, I never thought about QR codes, much less their application to libraries. But a lot of people have, and they are doing some pretty neat things. I especially like the way ACU Library uses them to enhance displays and provide more information about the books.
QR Codes to enhance displays & provide more information to patrons at ACU Libraries
Other libraries, such as the University of Huddersfield, are using them to provide text reference services, which I think is really cool, as I love the idea of extending reference beyond the desk/phone model.
Not sure at this point whether the QR codes will catch on here as they have in Japan, or if it's more of a fad. Either way, it seems like an easy & fun way to extend interest in the library resources, say, via book trailers tied to books on a display, or as a way to promote services, such as reference and research help.